11111111111111111 0111Olllll~ 111111111111111:111
`
`1 1
`
`11111 0'1111111111101
`
`United States Patent
`Helms
`
`[19]
`
`[11]
`
`[45]
`
`US005760760A
`Patent Number:
`Date of Patent:
`
`5,760,760
`Jun. 2, 1998
`
`[54]
`
`INTELLIGENT LCD BRIGHTNESS
`CONTROL SYSTEM
`
`[75]
`
`Inventor: Frank P. Helms. Round Rock. Tex.
`
`[73] Assignee: Dell USA, L.P•. Austin. Tex.
`
`[21] Appl. No.: 503,346
`
`Jul. 17, 1995
`
`[22] Filed:
`Int. CI.6
`[51]
`[52] U.S. CI
`[58]
`Field of Search
`
`G09G 3/36
`345/102; 345/63; 3451207
`345/63. 102. 101.
`34512l!. 207. 199; 348/602
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,029,982
`5,270,818
`5,315,695
`5,406,305
`
`7/1991 Nash
`12/1993 Ottenstein
`5/1994 Saito et aI.
`4/1995 Shimomura et aI
`
`345/101
`348/602
`345/63
`3451102
`
`FOREIGN PATENT DOCUMENTS
`
`3-94220A 4/1991
`5-19234A
`1/1993
`
`Japan.
`Japan.
`
`Primary Examiner-Xiao Wu
`Assistant Examiner-Xu-Ming Wu
`Attome); Agent, or Firm-Haynes and Boone L.L.P.
`ABSTRACT
`[57]
`
`Method and apparatus for automatically adjusting lhe bright(cid:173)
`ness level of an LCD based on the ambient lighting condi(cid:173)
`tions of lhe environment in which the LCD is being operated
`are disclosed. In a preferred embodiment. a photodetector
`located proximate the front of the LCD generates to bright(cid:173)
`ness control circuitry signals indicative of ambient lighting
`conditions. These signals are correlated to predetermined
`automatic brightness control values for use in controlling the
`brightness level of lhe LCD. Once the ambient light signals
`have been used automatically to set the brightness level of
`the LCD. user-selection of a different brightness level. either
`higher or lower. will override the automatic brightness
`control setting. In an alternative embodiment. a first photo(cid:173)
`detector is located proximate the front of lhe LCD and a
`second photodetector is located proximate lhe back of lhe
`LCD. In this embodiment. lhe brighter ambient condition is
`used to control the brightness level of the LCD. In another
`alternative embodiment.
`the brightness control circuitry
`comprises some form of artificial intelligence for "learning"
`a user's preferred brightness level. or range of brightness
`levels. in various ambient lighting conditions.
`
`8 Claims, 2 Drawing Sheets
`
`202
`\
`
`RAM
`
`I I
`
`204
`\
`
`200
`;
`
`CPU
`
`It
`
`206
`;
`
`DEVICES
`
`~8
`
`I I OTHER 1/0
`f
`
`{}
`BRIGHTNESS CONTROL CIRCUITRY
`
`MEMORY
`
`AL
`
`ABL
`
`jUlROCESSOR
`
`20~b
`
`20~a
`
`r - - -
`
`AID
`
`USBL
`
`AL
`
`2?::
`
`USBC
`\
`214
`
`AL
`\
`212
`
`210/ BC
`
`12
`
`LCD PANEL
`
`10
`~
`
`)6
`CONTROL
`KNOB
`
`PHOTO-
`DETECTOR
`
`~4
`
`RIM Ex. 1003, p. 1
`
`

`
`u.s. Patent
`
`Jun. 2, 1998
`
`Sheet 1 of 2
`
`5,760,760
`
`Fig. 1
`
`10
`'"
`
`202
`\
`
`RAM
`
`~
`
`I
`
`204
`\
`
`206
`/
`OTHER I/o
`DEVICES
`
`~
`
`200
`;
`
`CPU
`
`j
`
`208
`/
`
`BRIGHTNESS CONTROL CIRCUITRY
`
`MEMORY
`
`20~b
`
`AL
`
`ABL
`
`.
`
`/J.PROCESSOR
`
`I
`2040
`210../ BC,
`
`12
`
`LCD PANEL
`
`12
`
`10
`~
`
`}}
`CONTROL
`KNOB
`
`PHOTO-
`DETECTOR
`
`'\
`14
`
`USBL
`
`AL
`
`AID
`
`I
`204c
`
`USBC
`\
`214
`
`Al
`\
`212
`
`Fig. 2
`
`RIM Ex. 1003, p. 2
`
`

`
`U.8. Patent
`
`Jun. 2, 1998
`
`Sheet 2 of 2
`
`5,760,760
`
`Fig. 3
`
`300
`
`Fig. 5
`
`500
`
`CONVERT AL AND
`USBL SIGNALS AND
`INPUT TO ~PROCESSOR
`
`302
`
`LOOK UP ABL SIGNAL
`VALUE IN LOOK UP TABLE
`
`304
`
`SET BC = INDEXED ABL
`(ADJUST LCD)
`
`SET BC = USBL
`(ADJUST LCD)
`
`314
`
`LOOK UP ABL IN
`LOOK UP TABLE USING AL
`AND SET BC = INDEXED ABL
`(ADJUST LCD BRIGHTNESS)
`
`502
`
`LOOK UP ABL IN
`LOOK UP TABLE USING AL
`AND SET BC = INDEXED ABL
`(ADJUST LCD BRIGHTNESS)
`
`NO
`
`ADJUST lNDEXED ABL
`
`509
`
`SET Be = ADJUSTED ABL
`(ADJUST LCD BRIGHTNESS)
`
`510
`
`410
`
`Fig.
`10'
`~
`
`110'
`
`RIM Ex. 1003, p. 3
`
`

`
`5.760.760
`
`2
`ambient lighting conditions of the environment in which the
`PC is being used,
`
`SUMMARY OF THE INVENTION
`
`1
`INTELLIGENT LCD BRIGHTNESS
`CONTROL SYSTEM
`TECHNICAL FIELD
`The invention relates generally to liquid crystal displays
`(LCDs) and, more particularly. to a system for automatically
`adjusting the brightness of an LCD responsive to the amount
`of ambient light available during operation thereof.
`BACKGROUND OF THE INVENTION
`Liquid crystal displays (LCDs) are used in portable per(cid:173)
`sonal computers (PCs) and other electronic devices to dis(cid:173)
`play information. LCDs modulate light to create images
`using selectively transmissive and opaque portions of the
`display. the selection being controlled by passing electrical 15
`current through the liquid crystal material Transmissive-type
`LCDs are illuminated by an artificial backlight positioned
`behind the LCD glass to provide the contrast between the
`light transmissive and opaque portions of the display.
`The LCD backlight is one of the primary sources of power 20
`consumption in a portable PC and the power consumed by
`the backlight is directly related to the brightness level
`selected. Therefore. it would be advantageous. from a power
`consumption standpoint. to operate the PC with the LCD at
`the lowest possible brightness level at which the contents of 25
`the display can still be seen by the user. For example, in a
`particular portable PC model available from Dell Computer
`Corporation of Austin. Tex.. operating the PC with the LCD
`set to the minimum brightness level as compared to the
`maximum brightness level. can reduce overall power con- 30
`sumption of the PC by approximately twenty percent (20%).
`which in turn increases the runtime of the PC between
`battery charges by the same percentage. Specifically. assum(cid:173)
`ing that in the example just described the PC has a typical
`runtime between battery charges of 8 hours with the LCD set 35
`to the maximum brightness level. decreasing the brightness
`level to the minimum level will increase the runtime of the
`PC to 9.6 hours,
`In view of the foregoing. it is apparent that a user could
`significantly increase the runtime between battery charges of 40
`his or her portable PC by taking advantage of ambient
`lighting conditions that increase the Visibility of the LCD.
`that is. low ambient light. and decreasing the brightness
`level of the LCD whenever the PC is being operated in such
`lighting conditions. Specifically. it is obvious that the con- 45
`tents of an LCD can be much more easily viewed in a dark
`room than a bright one, Hence. a user could take advantage
`of that fact by decreasing the brightness level of the LCD
`whenever ambient lighting conditions permit and then sub(cid:173)
`sequently increasing the brightness level only when neces- 50
`sitated by bright ambient lighting conditions.
`While foregoing manual brightness adjustment presents a
`viable option for increasing the runtime of a PC between
`charges. it is deficient in certain respects. In particular. while
`a user may begin by operating the PC with the LCD 55
`brightness set to the minimum level necessary to enable the
`contents of the display to be perceived. after a user has
`moved with the PC to an environment in which the ambient
`the LCD be set to the
`lighting conditions require that
`maximum brightness level. the user will typically forget to 60
`decrease the brightness level upon returning to an environ(cid:173)
`ment in which the ambient lighting conditions would be
`conducive to such a decrease. As a result. the power savings
`are not as substantial as might be the case were the bright(cid:173)
`ness adjustment to occur automatically.
`Accordingly. what is needed is an intelligent LCD bright(cid:173)
`ness control system which automatically adjusts to the
`
`5
`
`The foregoing problems are solved and a technical
`advance is achieved by method and apparatus for automati(cid:173)
`cally adjusting the brightness level of an LCD based on the
`ambient lighting conditions of the environment in which the
`In a departure from the art. a
`LCD is being operated,
`10 photodetector located proximate the front of the LCD gen(cid:173)
`erates to brightness control circuitry signals indicative of
`ambient lighting conditions. These signals are correlated to
`automatic brightness control values for use in controlling the
`output of the backlight driver circuit which determines the
`brightness level of the LCD.
`invention. signals
`In one embodiment of the present
`indicative of a user-selected brightness level are also input
`to the brightness control circuitry and taken into account in
`to the adjustment of the brightness level of the LCD. In one
`aspect of the invention. once the ambient signals have been
`used automatically to set the brightness level of the LCD.
`subsequent user-selection of a different brightness level.
`either higher or lower. will override the automatic brightness
`control setting.
`In an alternative embodiment. a first photodetector is
`located proximate the front of the LCD and a second
`photodetector is located proximate the back of the LCD. In
`this embodiment. the brighter ambient condition is used to
`control the brightness level of the LCD. This embodiment is
`especially usefull in situations in which light is directed
`toward the back of the LCD. and hence toward the user's
`eyes, which light. while affecting the visibility of the LCD.
`might not be detected by the first photodetector.
`In another alternative embodiment. the brightness control
`circuitry comprises some form of artificial intelligence for
`"learning" a user's preferred brightness level. or range of
`brightness levels. in various ambient lighting conditions.
`A technical advantage achieved with the invention is that
`it provides increased run-time between battery charges by
`lowering the brightness level of an LCD during use in low
`ambient lighting conditions.
`Another technical advantage achieved with the invention
`is that the adjustment of the brightness level occurs auto(cid:173)
`matically without user intervention. thereby reducing the
`possibility that a user may set the brightness level at a
`maxium level during use in high ambient lighting conditions
`and subsequently neglect to lower the level upon returning
`to a low ambient lighting condition.
`Another technical advantage achieved with the invention
`is that. in at least one embodiment. the user may override the
`automatic brightness control setting using a conventional
`LCD brightness control means.
`Yet another technical advantage achieved with the inven(cid:173)
`tion is that the brightness control circuitry can be configured
`to "learn" a user's preferred brightness settings in various
`ambient lighting conditions. thereby obviating the need for
`the user to readjust the brightness level and override the
`automatic brightness control setting each time such ambient
`lighting conditions are entered.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is a front perspective view of a portable personal
`65 computer (PC) embodying features of the present invention.
`FIG. 2 is a system block diagram of the portable PC of
`FIG. 2.
`
`RIM Ex. 1003, p. 4
`
`

`
`5.760.760
`
`3
`FIG. 3 is a flowchart of the operation of brightness control
`circuitry for implementing the method of the present inven(cid:173)
`tion.
`FIG. 4 is a rear perspective view of a portable PC
`embodying features of an alternative embodiment of the
`present invention.
`FIG. 5 is a flowchart of the operation of brightness control
`circuitry for implementing an alternative embodiment of the
`method of the present invention.
`
`DETAaED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`FIG. 1 illustrates a portable personal computer (PC) 10
`embodying features of the present invention and comprising
`a base 11 including a keyboard lla. a liquid crystal display
`panel (LCD) 12 disposed in a lid portion 13 of the PC 10.
`and at least one photodetector or light sensor 14 disposed on
`the same side of the lid portion 13 proximate the LCD 12.
`for detecting a level of ambient light directed toward the
`front of the LCD 12 and for generating signals indicative of
`same. A user-selected brightness control level may be input
`via conventional methods and stored in a nonvolatile
`memory device, as shown in"FIG. 2. foe enabling the user
`manually to adjust the brightness level of the LCD 12.
`FIG. 2 is a system block diagram of the PC 10 of FIG. 1.
`As shown in FIG. 2. the PC 10 comprises a CPU 200, system
`RAM 202. brightness control circuitry 204. and other I/O
`devices 206, including the keyboard lla (FIG. 1), electri(cid:173)
`cally interconnected via a bus 208.
`In the preferred
`embodiment. the brightness control circuitry comprises a
`microprocessor 204a. memory 204b, and an analog-to(cid:173)
`digital ("ND") converter 204c foe purposes that will sub(cid:173)
`sequently be described in detail.
`An output of the microprocessor 204a is electrically
`connected to the Backlight driver circuitry 213 in a conven(cid:173)
`tional manner for generating brightness control or "BC,"
`signals thereto via a line 210 for controlling the brightness
`level of the LCD 12 at any given time. In addition. analog
`signals generated by the photodetector 14 indicative of the
`level of ambient light striking the front of the LCD 12
`(hereinafter "ambient light" or "AL" signals). as well as a
`digital signal indicative of the brightness level selected by
`the user (hereinafter "user-selected brightness level" or
`"USBL" signal) and stored in a nonvolatile memory device.
`such as NVRAM 211. are input to the brightness control
`circuitry 204 on lines 212, 214. respectively. The analog AL
`signals are converted to digital signals by the analog-to(cid:173)
`digital converter 204c and then input to the microprocessor
`204a.
`A plurality of automatic brightness level ("ABL") signal
`values, each of which corresponds to a particular one of a
`plurality of various possible AL signal values. are stored in
`the memory 204b. It will be understood that the ABL signal
`value associated with each of the AL signal values will be
`determined empirically and will depend. at least partially. on
`the relevant parameters of the particular LCD 12. as well as
`a SUbjective determination of the optimum LCD brightness
`level for operation in the given ambient lighting condition.
`In one embodiment. the ABL signal values are stored in the
`memory 204b as a lookup table indexed by the input AL
`signal value, such that input of an AL signal thereto via the
`microprocessor 204a results in the output therefrom of the
`corresponding ABL signal. although various other manners
`of implementation are anticipated. In any event. once the
`microprocessor 204a accesses from the memory 204b the
`ABL signal value corresponding to the AL signal
`input
`
`4
`thereto. it outputs to the Backlight driver circuitry 213 an
`appropriate BC signal for adjusting the brightness level of
`the LCD 12 in accordance with the levels indicated by the
`USBL and AL signals. as will be described in detail with
`5 reference to FIG. 3.
`FIG. 3 is a flowchart of the operation of the brightness
`control circuitry 204 foe inplementing the preferred embodi(cid:173)
`ment of the present invention. It should be understood that
`instructions for execution by the microprocessor 204a for
`10 inplemnenting the invention are preferably stored in
`memory 204b. Execution begins in step 300 when the LCD
`12 is turned on. In step 302. after the analog AL signal
`generated by the photodetector 14 has been converted to a
`digital signal by the NO converter 204c and input to the
`microprocessor 204a. it is used to index the ABL signal
`15 lookup table (not shown) stored in the memory 204b. Also
`in step 302. the BC signals output to the backlight driver
`circuitry 213 for controlling the brightness level of the LCD
`12 is set to correspond to the ABL signal indexed by the AL
`signal In this manner, the brightness level of the LCD 12 is
`20 adjusted according to the current ambient lighting conditions
`in which the PC 10 is being operated. It should be under(cid:173)
`stood that. alternatively. upon power up of the LCD 12. the
`Be signal may initially be set to equal the value of USBL as
`stored in the NVRAM 211. such that the brightness level of
`25 the LCD 12 is set to correspond to the previous user-selected
`level. rather than the ambient lighting conditions.
`In step 304. a determination is made whether the AL
`signal has changed.
`indicating that the ambient lighting
`conditions have changed. If so. execution proceeds to step
`30 306. In step 306. the new AL signal is again used to index
`the ABL signal lookup table (not shown) stored in the
`memory 204b. Also in step 306. the BC signals output to the
`backlight driver circuitry 213 foe controlling the brightness
`level of the LCD 12 is set to correspond to the ABL signal
`35 indexed by the AL signal thereby adjusting the brightness
`level of tbe LCD 12 according to tbe new ambient lighting
`conditions. Execution then proceeds to step 308. Similarly.
`if in step 304. it is determined that the AL signal has not
`changed. indicating that no adjustment for ambient lighting
`40 conditions is necessary. execution proceeds directly to step
`308.
`In step 308. a determination is made whether the USBL
`signal has changed. If the USBL signal has not changed.
`execution returns to step 304. In contrast, if the USBL signal
`45 has changed.
`indicating that
`the user has attempted to
`manually change the brightness level of the LCD 12, execu(cid:173)
`tion proceeds to step 310. In step 310, the BC signal output
`to the backlight driver circuitry 213 is set to correspond to
`the USBL signal. Once the brightness of the LCD 12 has
`50 been set to the level indicated by the USBL signal in step
`310. execution returns to step 304.
`In this manner.
`the brightness control circuitry 204
`ensures that the brightness level of the LCD 12 is always
`automatically set to the level dictated by the current ambient
`55 lighting conditions. unless the user selects a different bright(cid:173)
`ness level subsequent to a change in the ambient lighting
`conditions. in which case the level selected by the user is
`used to control the brightness level of the LCD 12. As a
`power saving measure. an additional step could be added in
`60 which a comparison is made between the level of the AL and
`USBL signals and. responsive to the comparison. the bright(cid:173)
`ness level of the LCD 12 is dictated by the lower (ie..
`dimmer) of the two signals. It should be noted. however. that
`this may result in a situation in which the LCD 12 cannot be
`65 read. for example, where a user moves from low to high
`ambient lighting conditions without manually readjusting
`the brightness setting.
`
`RIM Ex. 1003, p. 5
`
`

`
`5.760.760
`
`10
`
`5
`FIG. 4 is a rear perspective view of a portable PC 10'
`embodying features of an alternative embodiment of the
`present invention. In particular. in addition to comprising all
`of the same features of the PC 10 shown in FIG. 1. including
`a base 11'. a keyboard lId. an LCD 12' disposed in a lid 13'.
`a first photodetector 14' and a user-actuatable brightness
`control means (not shown). the PC 10' further comprises a
`second photodetector 410 disposed on the opposite side of
`the lid 13' as the LCD 12' and first photodetector 14'. for
`detecting ambient light directed toward the back side of the
`LCD 12' and toward a user's eyes.
`In the alternative embodiment. the greater of an AL signal
`generated by the photodetector 14' and an AL signal gener(cid:173)
`ated by the photodetector 410 is used to index the lookup
`table comprising ABL signal values. as described with 15
`reference to FIGS. 2 and 3. In this manner. the brighter
`ambient lighting condition is used to determine the ABL
`signal value for use in adjusting the brightness level of the
`that. with this alternative
`LCD 12'. It will be apparent
`embodiment. the user is insured that the contents of the LCD 20
`12' will be visible where, for example. the area behind the
`LCD 12' is highly illuminated. but the area in front of the
`LCD 12' is not. This might not be the case absent the second
`photodetector 410 as shown in FIG. 4. the brightness level
`of the LCD 12' would most likely be set too low for the user 25
`comfortably to view the contents thereof. Alternatively. a
`weighted average of the AL signals generated by the pho(cid:173)
`todetectors 14' and 410. as computed by the microprocessor
`402a. could be used to index the lookup table.
`In another alternative embodiment of the invention. as 30
`described with reference to FIGS. 2 and 5. the brightness
`control circuitry 204 comprises some fonn of artificial
`intelligence designed to adjust the lookup table ABL entries
`stored in the memory 204b according to current and previ(cid:173)
`ous USBL signals generated in response to a particular 35
`detected ambient lighting conditions. In this manner. the
`brightness control circuitry 204 "learns" the users preferred
`settings for particular lighting conditions. thereby minimiz(cid:173)
`ing the number of times the user must manually adjust the
`brightness level to override the automatic settings.
`Referring to FIG. 5. execution begins in step 500 when the
`LCD 12 is turned on. In step 502. once the analog AL signal
`g~nerated by the photodetector 14 is converted to a digital
`SIgnal by the NO converter 204c and input to the micro(cid:173)
`processor 2040. it is used to index the ABL signal lookup 45
`table (not shown) stored in the memory 204b. Also in step
`502. the BC signal output to the backlight driver circuitry
`213 for controlling the brightness level of the LCD 12 is set
`to correspond to the ABL signal indexed by the AL signal.
`thereby adjusting the brightness level of the LCD 12 accord- 50
`ing to the current ambient lighting conditions. Again. it
`should be understood that upon power up of the LCD 12. the
`BC signal may initially be set to correspond to the value of
`USBL as stored in the NVRAM 211. rather than the value of
`the AL signal.
`In step 504. a determination is made whether the AL
`signal has changed. indicating that the ambient lighting
`conditions have changed. If so. execution proceeds to step
`506. In step 506. the new AL signal is used to index the ABL
`signal lookup table (not shown) stored in the memory 204b. 60
`~so ~n step 506. the BC signal output to the backlight driver
`ClfCUltry 213 for controlling the brightness level of the LCD
`12 is set to correspond to the ABL signal indexed by the new
`AL signal. thereby adjusting the brightness level of the LCD
`12 according to the current ambient lighting conditions. 65
`Execution then proceeds to step 508. Similarly. if in step
`504. it is determined that the AL signal has not changed.
`
`6
`indicating that no adjustment for ambient lighting conditions
`is necessary. execution proceeds directly to step 508.
`In step 508, a determination is made whether the USBL
`signal has changed. If the USBL signal has not changed.
`5 execution returns to step 504. In contrast. if the USBL signal
`has changed.
`indicating that
`the user has attempted to
`manually change the brightness level of the LCD 12. execu(cid:173)
`tion proceeds to step 509. In step 509. the lookup table entry
`corresponding to the current AL is adjusted according to the
`present USBL. In addition. previous USBL signals gener(cid:173)
`ated when the present ambient lighting condition is encoun-
`tered are also preferably taken into account during the
`adjustment. Once the lookup table entry has been adjusted.
`execution proceeds to step 510. In step 510. the Be signal
`output to the backlight driver circuitry 213 is set to corre(cid:173)
`spond to the USBL signal. Once the brightness of the LCD
`12 has been set to the level indicated by the USBL signal in
`step 510. execution returns to step 504.
`In this manner. the brightness control circuitry 204 is able
`to take into account the user's preferences with respect to
`preferred brightness control settings in particular ambient
`In the preferred embodiment.
`the
`lighting conditions.
`method illustrated in FIG. 5 is designed to constantly
`attempt to converge on the user's preferred setting for each
`range of ambient lighting conditions. thereby minimizing
`the necessity that the user will need to manually adjust the
`LCD 12 brightness setting.
`It is understood that the present invention can take many
`forms and embodiments. The embodiments shown herein
`are intended to illustrate rather than to limit the invention. it
`being appreciated that variations may be made without
`departing from the spirit or the scope of the invention. For
`example. the LCD brightness control circuitry 204 could
`comprise some fonn of artificial intelligence. e.g.. a neural
`network. for "learning" the user's preferred brightness set(cid:173)
`tings in various ambient lighting conditions. as indicated by
`the control means setting. such that when the settings are
`later re-encountered.
`the LCD 12 will be automatically
`40 adjusted to the user's preferred brightness setting.
`Alternatively. the brightness control circuitry 204 could be
`simplified to provide a direct linear control signal of mea(cid:173)
`sured light to LCD brightness level. thus eliminating the
`need for the NO converter 204c and microprocessor 2040.
`Although illustrative embodiments of the invention have
`been shown and described. a wide range of modification.
`change and substitution is intended in the foregoing disclo(cid:173)
`sure and in some instances some features of the present
`invention may be employed without a corresponding use of
`the other features. Accordingly. it is appropriate that the
`appended claims be construed broadly and in a manner
`consistent with the scope of the invention.
`What is claimed is:
`1. In an electronic device having a liquid crystal display
`55 (LCD). an apparatus for automatically adjusting the bright(cid:173)
`ness of the LCD in response to ambient lighting conditions.
`the apparatus comprising:
`a brightness control circuitry including a microprocessor
`and a memory;
`means for manually adjusting the brightness of the LCD
`and generating a selected brightness level signal to the
`microprocessor;
`a first photodetector for detecting a level of ambient light
`directed toward a first side of the LCD and for gener(cid:173)
`ating a first ambient light signal to the microprocessor;
`means for converting the ambient light signal for input
`into the microprocessor;
`
`RIM Ex. 1003, p. 6
`
`

`
`5.760.760
`
`7
`lhe memory having automatic brightness level signals
`indexed by the ambient light signals;
`means for determining the lower value of lhe selected
`brightness level signal and the automatic brightness
`level signal; and
`means for setting the brightness level of the LCD to
`correspond to lhe lower level indicated by the auto(cid:173)
`matic brightness level signal and the selected bright(cid:173)
`ness level signal.
`2. The apparatus of claim 1 wherein said electronic device
`is a portable personal computer.
`3. The apparatus of claim 1 wherein said first side is a
`front side of said LCD.
`4. An apparatus for automatically adjusting the brightness
`of a liquid crystal display (LCD) in response to ambient 15
`lightning conditions, the apparatus comprising:
`a brightness control circuitry including a microprocessor,
`a memory and an analog-to-digital (ND) converter;
`means for manually adjusting the brightness of the LCD 20
`and generating selected brightness level signals to the
`microprocessor;
`a first photodetector for detecting a level of ambient light
`directed toward a first side of the LCD and for gener(cid:173)
`through the ND 25
`ating a first ambient
`light signal
`converter to the microprocessor;
`the memory having automatic brightness level signals
`stored therein indexed by the first ambient light signal;
`means for generating a brightness control signal to cor-
`respond to the selected brightness level signal;
`means for generating a brightness control signal to cor(cid:173)
`respond to the automatic brightness level signal;
`means for determining the lower value of the selected
`brightness level signal and the automatic brightness
`level signal; and
`
`30
`
`8
`means for setting the brightness level of the LCD to
`correspond to the lower level indicated by the auto(cid:173)
`matic brightness level signal and the selected bright(cid:173)
`ness level signal.
`5. The apparatus of claim 4 wherein said means for
`manually adjusting is a function key of said electronic
`device.
`6. In an electronic device having a liquid crystal display
`10 (LCD). a method of automatically adjusting the brightness
`of the LCD in response to ambient lighting conditions. the
`method comprising the steps of:
`manually adjusting the brightness level of the LCD and
`generating a selected brightness level signal to a micro(cid:173)
`processor;
`detecting a level of ambient light directed toward one side
`of the LCD and generating an ambient light signal to
`the microprocessor;
`storing an automatic brightness level signal in a memory;
`to lhe
`indexing lhe automatic brightness level signal
`ambient light signal;
`determining the lower value of the selected brightness
`level signal and lhe automatic brightness level signal;
`and
`setting the brightness level of the LCD to correspond to
`the lower value indicated by the automatic brightness
`level signal and lhe selected brightness level signal.
`7. The method of claim 6 wherein said electronic device
`is a portable personal computer.
`8. The melhod of claim 6 wherein said first side is a front
`side of said LCD.
`
`*****
`
`RIM Ex. 1003, p. 7